Insecticide



Patented Sept. 3, 1940 PATENT OFFICE INSECTICIDE William F. Hester, Drexel Hill, Pa., assignor to Rohm & Haas Company, Philadelphia, Pa.

N Drawing.

Application February 25, 1939, Serial No. 258,469

Claims. (01167-30)- The object of the invention is to provide im-- proved insecticidal compositions of general application which can be used in low concentration to control pests without injury to plant foliage.

A further object is to provide an organic insecticide of the so-called stomach type to be used in place of lead arsenate, etc. against chewing in- 5 sects such as bean beetles, etc.

A still further object relating to and growing out of the accomplishing, of the foregoing objects is to provide an eflicient method for the preparation of phenyl benzyl ethers in high yields.

The phenyl ethers and benzyl ethers have heretofore been proposed as insecticidal principles. However, they have never been used extensively for the purpose because of their relatively low toxicity as compared to other known insecticidal principles and because of the severe plant injury that results from their use in sufficient quantities to be effective against insects. It has now been found, however, that the introduction of certain substituents into either the phenyl or benzyl group has the chest of greatly reducing the corrosiveness of phenyl benzyl ethers to plant foliage, while in many instances increasing the toxicity of the base compound. By a series of many 40 such as strongly acid or basic groups and the phenolic hydroxyl group-either greatly reduce plant foliage injury as compared with equal proportions of the unsubstituted compound or so greatly increase the toxicity that by using smaller 45 dosages, plant injury can be avoided while maintaining efiective insect control. Substituents of a total relative weight less than 30 are apparently too small to be effective.

Among the substituent groups that have been 50 found to produce this effect may be mentioned the alkyl groups of more than 2 carbon atoms,

the alkylene groups of similar carbon content,

hydroaromatic groups, aralkyl groups, alkoxy groups, aryloxy groups, acyl groups, halogen 55 atoms, nitro groups, amino groups that have been neutralized, acylamino, alkylamino and aralkylamino groups, and carboxyl and sulfonic groups that have been neutralized as by being converted to a salt, ester, or lactone group. It-has also been found that when the single aromatic ring of 5 either the benzyl or phenyl group is replaced with a polynuclear aromatic group such as the naphthyl radical, the second ring produces the effect of a substituent group. Such polynuclear groups are accordingly hereinafter considered as 10 substituted phenyl groups. The substituent groupmay be in either the ortho, meta, or paraposition to the CH2O linkage but preferably is in the para where its influence in stomach poisons is generally the greatest. In compounds 15 to be used solely as contact insecticides, the substituent in the ortho position is preferred. A plurality of substituents either similar or dissimilar and either situated on the one or on both aromatic rings, is included. Compounds 20 with substituents in the methylene group are also included.

These compounds may be made in any of the known methods all of which in principle involve condensing in an alkaline medium the properly 5 substituted phenol with benzyl chloride containing the desired substituents, if any, in the benzyl group. An improved method that has been found particularly satisfactory and which is a feature of this invention is the utilization of dimethylo aniline in amounts substantially less than equimolecular with the benzyl chloride in conjunction with an alkali metal hydroxide as the condensing agent. In general this improved method comprises mixing the phenol or the sodium salt of the phenol being condensed, a slight molar excess of the benzylchloride, dimethylaniline in amounts approximately one half the molar quantity of the phenol or benzyl chloride, and an amount of alkali metal hydroxide equivalent to the amount of benzyl-chloride in aqueous emulsion, heating until reaction is substantially complete, filtering, and washing, and recrystallizing or otherwise purifying the product. The proportions here given are not critical but rather are those that have been found to give in general the most economical yields. Larger or smaller amounts of dimethylaniline may be used. ,=The following examples are given to illustratethis method of preparation, Wide variations in them being permissible.

EXAMPLE 1.Preparaticm of C6H5C'H20c6H4- N O2-4.A mixture of 3360 g. 14 mols) of 81.8% paranitro-sodium phenolate dihydrate, 2050* g. (15.4 mols) of benzyl chloride, 848 g. (7 mols) of dimethylaniline, 56 g. (1.4 mols) of sodium hydroxide in 10 l. of water, was heated on a boiling water bath for 6 hours, with stirring. It was allowed to stand overnight, and then was filtered. The filtrate was neutral to litmus. The cake was ground and washed with 609 cc. (7 mols) of concentrated hydrochloric acid in 3 l. of water, and then with 400 cc. (4.7 mols) of acid in 10 l. of water. The solid was Washed twice with 2 l. of methanol, once with 3 l. of petroleum ether (B. P. 60-100" C.) and then recrystallized from isopropanol, using 300 cc. for each g. of solid. The recrystallized product was 2718 g., 82% yield, M. P. 10545", which agrees with the melting point recorded in the literature. When the dimethylaniline was replaced with sodium hydroxide the yield dropped to 46%.

EXAMPLE 2.-Prepara.tion of C6H5CH2OC'6H4- CcH5-2.A mixture of 2040 g. (12 mols) of orthophenylphenol, 1670 g. (13.2 mols) of benzyl chloride, 530 g. (13.2 mols) of sodium hydroxide, 727 g. (6 mols) of dimethylaniline, in 10 l.. of water, was heated to 100 C. and stirred at this temperature for 4 hours. The mixture was allowed to cool overnight and the top aqueous layer was siphoned oil. A mixture of 3.5 l. of ethylene dichloride and 3.5 l. of water contain ing 50 g. of sodium hydroxide was added to the bottom layer, and after stirring, allowed to separate. The bottom layer was washed with 7 1 of water and then three times with 520 cc. (6 mols) of concentrated hydrochloric acid in 3.5 l. of water. The bottom layer was washed three times with 7 l. of water. The ethylene dichloride solution was dried over calcium chloride, concentrated, dissolved in 6.3 l. of methanol, and cooled to 0. The crystalline product was filtered 01f and air-dried. The total weight was 2380 g., or 92.3% of. the theoretical yield. Melting point 42-3 C. When 363 g. (3 mols) or 0.25 molecular equivalent of dimethylani line was used, the yield was only 79%.

EXAMPLE 3.Preparation of CsHsCHzOCcHt- C(C'H3)3-4.-A mixture of 150 g. (1 mol) of paratertiary butylphenol, 62 g. (0.5 mol) of dimethylaniline, 139 g. (1.1 mol) of benzyl chloride, 44 g. (1.1 mol) of sodium hydroxide in 540 cc. of water, was stirred and heated on a boiling water bath for 4 hours. The mixture was rapidly cooled and to it was added 50 cc. (0.5 mol) of concentrated hydrochloric acid. The solid was washed twice by melting in the presence of 0.5 mol of hydrochloric acid in 700 cc. of water, and then washed twice with water. It was recrystallized from 350 cc. of methanol, giving 200 g. or 83% yield. Melting point 64 C.

EXAMPLE 4.Preparation of 4-NO2CeH4C'H2- OC'eH-1C' (CH3) s-4.--Crude paranitrobenzyl bro-- mide was prepared by the method of Org. Syn. XVL, 54.

A mixture of 400 g. of this crude material (1.33 mol), 200 g. (1.33 mol) of paratertiary butylphenol, 60 g. (1.5 mol) of sodium hydroxide in 1 l. of water, was heated on a boiling water bath and stirred for 4 hours. After cooling over night, the resulting solid was transferred to a Biichner funnel and washed with 100 cc. of 50% methanol and with 100 cc. of methanol. A small amount of black oil filtered through. The product was then recrystallized from 800 cc. of methanol twice as light tan crystals melting at butylphenyl ether was 311 g., or 82%.

The best method of using these phenyl benzyl ethers in insecticidal compositions will depend to The yield of 4'-nitrobenzyl I-tertiary.-

Parts by weight (A) Active ingredient 1 Talc or lime 98 Spreader (cetyl dimethyl ethyl ammonium ethyl sulfate) l (B) Active ingredient l Alum sludge 18 Lime l8 Soy bean 0i1 3 Sprays to combat chewing insects can be made by applying a larger quantity of the active ingredient to a powder adding an emulsifying agent and dispersing in sufficient water to reduce the quantity of active ingredient in the final spray to the desired concentration. A suitable formula for this type of spray is Parts 1 part active ingredient deposited on 2 parts magnesium carbonate 3 A commercial emulsifying agent sold under the name DX spreader 0.5 Water 96.5

Sprays used to repel sucking insects such as red spiders by contact can be made by dissolving the active ingredient in an organic liquid that does not affect the foliage, adding an emulsifying agent, and dispersing the solution in sufiicient water to reduce the concentration of active ingredient to the desired point. A suitable formula for this type of spray is- Parts .25 part active ingredients and .25 part emulsifying agent dissolved in .50 part pine oil 1 Water 100-300 Spray used to combat flying insects such as common flies, mosquitoes, etc., can be made by merely dissolving the proper amount of active ingredients, 15%, in an organic solvent such as kerosene to which a spreading agent may be added if desired.

The tables given below show the results of a number of tests using variously substituted phenyl benzyl ethers in combating the more common insects. There is also included for purposes of comparison the results obtained when the unsubstituted compound is used.

Table I gives the results of toxicity tests of 1% dusts or sprays against bean beetle larvae. These tests were made under controlled temperature humidity and light conditions. The bean plants were sprayed or dusted 24 hours before the Mexican bean beetle larvae were introduced. Counts were made at the end of 96 hours. At least three experiments were run on each compound and the figures given are the average.

arsenate.

Table I x Mg arscnate Plant Kill per- Incap. Formula in cent percent Km, heap" percent percent C5H5CH2O OQH5 1. Severe. 13 6 1O 3 C6II5CH2OC6H4C(CH3)3-4 76 10 40 3 CaH5CHg0C'aH4C(CHQgCzIh-i 80 13 40 3 CQHECHQOC51I4C1I(CH2)5-4' 73 13 40 3 CaH5CHzOCsH.gCuH5-2.. N0... 46 23 43 23 CaH5C-Il;OCaH CI-4 I. S1ight 16 43 23 CuH5CHz0C5H4NO2-4 I I N 83 10 40 3 CaHsCHzOCoHfl-Q, 6-(NO1)z-4-C(CH3)gCHzC(CH3)3) I. 53 10 35 13 CuH5CH2OCgH3CH3-2-NO24 60 30 3O 6 cuH5CHgOCeH4COCaH5-4 I 1 I 73 23 30 6 0011501120CuH (-2-N0z)SOaNHaCaHrCl-L 16 23 30 6 4-NOzCaH4CH2OC5H4C(CH3)34 I I I I 93 3 35 13 4-NOzC5H4CHz0C5H4OH3-4... M 66 I. 35 13 1-C1nH7CHzOCtH5 I 30 23 30 6 (CuH5)zCHOCuH5 10 20 35 13 'Table II gives the results of a similar series of tests performed on bean beetle adults. These tests were made under the same conditions given for Table I excepting that the bean beetle adults were used instead of the larvae.

In the foregoing tables the tests summarized used the substituted phenyl benzyl ethers as stomach poisons. The tables that follow show the results of tests in which they are used 'as contact poisons. Table IV shows theirtoxicityagainst Table II Mg arsenate Plant Kill, ncap., Formula inj. percent percent Kin Incap.

percent percent CsH5CH2OCeHa 2O CeH5CH2OCaH4COCHa-4 Cal-IsCHzOCoILCsHy-Z CuH5CH2OCaH4Cl-4. CaH5CH2OC5H4NOz-4 CsHaCH2OCuH4NO2" CtHs 2 1oH1-1 lfl ll Q B AC(CH3)2CH2C(OH3)3'4 2-CmHnCH2OCuH4CsH5-2 15 13 10 20 43 13 10 20 43 30 23 16 16 13 15 23 26 10 20 2O 13 36 16 30 16 13 55 50 30 30 35 30 3O 26 2O Table III shows the efiectiveness of the new insecticides against cabbage worm larvae. The procedure was the same as for Tables I and II except the test organism was the larva of the diamond-back cabbage worm.

Table III red spiders. In all these tests theinsecticide was applied as an emulsion spray in which the toxic material being tested was diluted 1:1200 times unless otherwise indicated. At this dilution no foliage injury was observed with any of the Formula Mg arsenate Percent kill i f i Incap CaHsCHzOCaHs Lead arsenate used in check in place of magnesium arsenate.

CaHsCHzOCmHv-l (dilution 1:2400

materials tested. The tests were made by spraying the emulsion under standard conditions on foliage infested with red spiders (Araneida). The host plants were ageratum, bean, and cabbage. The plants were allowed to stand for 24 hours and then counts were made on five pieces of the plant for each test. The figures given are the average percent kill.

Table V summarizes similar tests against mealy bugs. The tests were conducted in the same manner as in Table IV excepting that the organisms were mealy bugs and the host plant coleus.

Table V Per- Formula cent CaHsCHzOCaHs CsH5CH2OCuH4CH3-IL CgHsCHZOCeILCHa-Z.

Table VI summarizes tests performed as in Tables IV and V on aphis infesting nasturtium and cabbage plants.

Table VI Percent kill Formula CsHsCHgOCuHrNHCOCH3-4. (i NOgCgHaCHzOCaHr)1C(CH 1-CmH7CH2OCgH NO24 -CmHuCH2OCaH4C(CH3)a-4 (dilution 1:1600) kill Finally, Table VIE gives data on fly tests conducted by the standardized procedure of the approved Peet-Grady method. In these tests a 2% solution of the indicated phenyl benzyl ether in Additional compounds that have been tested I and which show a much reduced corrosiveness to plants as compared to the unsubstituted phenyl benzyl ethers without sacrifices of toxicity are From the data herein contained it is apparent that those phenyl benzyl ethers having a substantially neutral substituent of atomic or relative group weight of at least 30 or less corrosive to plants than the unsubstituted or less highly substituted ones. Also that they have a wide range of usefulness in combating insect pests. Additional substituent groups and other ways of using those herein disclosed will be apparent to persons skilled in the art. It is intended that such modifications as do not depart from the basic cencept of the invention are to be included in the appended claims.

I claim: 1. An insecticidal composition containing a phenyl benzyl ether having the formula wherein the R's are aromatic hydrocarbon groups and R is selected from the group consisting of aliphatic hydrocarbon groups containing at least two carbon atoms, alkoxy groups and cycloalkyl groups.

2. An insecticidal composition containing a phenyl benzyl ether having the formula CsHsCHzQCaHa-R wherein R is an alkyl group containing. at least two carbon atoms.

4. An insecticidal composition containing a cycloalkyl phenyl benzyl ether.

5. An insecticidal composition containing a. 5

tertiary amyl phenyi benzyl ether.

WILLIAM F. HESTER. 

